// alert("Hello World!");

//单行注释

/*
    多行
    注释
 */

//console
console.log("Hello World!");
console.log(123);
console.log(true);

var greeting = "Hello";
console.log(greeting);
console.log([1, 2, 3, 4]);
console.log({a: 1, b: 2});

//打印对象
console.table({a: 1, b: 2});

console.error("this is some error");

console.clear();

console.warn("this is a warning");

